The X Prize Foundation - which helped kickstart commercial passenger space travel - is funding another $10m prize to find the most fuel-efficient car.
The Automotive X Prize, or rather the "Progressive Insurance Automotive X PRIZE", aims to find a realistic super-efficient vehicle. It aims to find cars which actually just go into production, rather than just prototypes showcasing new technology. It also aims to offer a level playing field for both amateurs and manufacturers.
There are two categories; mainstream cars, with four wheels and room for four or more passengers, and alternative vehicles, which must carry two or more passengers but can have any number of wheels.
Both classes must achieve at least 100 miles per gallon or equivalent, give out less than 200 grammes per mile and satisfy US EPA Tier II, bin 5 standards. The production of the cars should also be equivalent to typical vehicles.
The vehicles should be reasonably priced too, assuming production of 10,000 a year, and should have features likely to attract the average consumer.
Some 66 teams have already paid $5,000 to register for the prize. Most entries are from the US although there are two from Northampton in the UK and one from Germany.
Entries are pretty varied - from electric three-wheelers that look like souped-up Sinclair C5s, to drive systems that can be retro-fitted to any medium-sized car. The Avion is a very lightweight and aerodynamic fibreglass body designed to be fitted with recycled engines and gearboxes.
All cars will have to run on either petrol, diesel, electricity, natural gas, bio-diesel and E85 - ethanol and petrol.